Myxococcus xanthus is an excellent prokarytoic system for the study of the regulation of development. M. xanthus show a developmental cycle which is similar to the eukaryotic slime molds such as Dictyostelium discoideum. However, there are several distinct advantages to study of development of M. xanthus, since it is a simple gram-negative bacterium. We propose to study morphogenesis and the molecular mechanism of control of gene expression during development using M. xanthus as a model system. For this purpose, we attempt the following approaches; (a) characterizaton of development-specific proteins; identification, purification and characterization, (b) characterizatin of development-specific RNAs, (c) identification and cloning of development-specific genes, (d) nucleotide sequences of development-specific genes, and (e) characterization of development-specific membrane components, which are essential for cell-cell interaction and morphogenesis during development.